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Actuator Materials
Published in Kenji Uchino, Micro Mechatronics, 2019
Quartz is a well-known piezoelectric material. Alpha (α) quartz belongs to the triclinic crystal system with point group 32 and undergoes a phase transition at 537°C to its beta (β) form, which is not piezoelectric. One particular cut of quartz, the AT-cut, has a zero temperature coefficient. Quartz oscillators, made from an AT-cut crystal and operated in thickness shear mode, are used extensively for clock sources in computers, and frequency-stabilized devices are used in televisions and video recorders. An ST-cut quartz, when used as a substrate for surface acoustic waves propagating in the x direction will also have a zero temperature coefficient for such waves, thus making it suitable for frequency-stabilized surface acoustic wave devices. Another distinctive characteristic of quartz is its exceptionally high mechanical quality factor, Qm > 105.
Piezoelectric Devices
Published in Kenji Uchino, Ferroelectric Devices, 2018
Quartz is a well-known piezoelectric single crystal material. α-quartz belongs to the triclinic crystal system with point group 32 and has a phase transition at 537°C to its β-form which is not piezoelectric. Quartz has a cut with a zero temperature coefficient. For instance, quartz oscillators, operated in the thickness shear mode of the AT-cut, are used extensively for clock sources in computers, frequency-stabilized ones in TVs and VCRs. On the other hand, an ST-cut quartz substrate with X-propagation has a zero temperature coefficient for SAW, and so is used for SAW devices with high-stabilized frequencies. Another distinguished characteristic of quartz is an extremely high mechanical quality factor QM > 105.
Introduction to Phosphors, Rare Earths, Properties and Applications
Published in Vijay B. Pawade, Sanjay J. Dhoble, Phosphors for Energy Saving and Conversion Technology, 2018
Vijay B. Pawade, Sanjay J. Dhoble
Alumina (Al2O3) and silica (SiO2) are the two most plentiful minerals in the earth’s crust. The class of minerals containing aluminum oxide and silicon oxide is called aluminosilicates. Their chemical formulae are often expressed as xAl2O3.ySiO2.zH2O. The study of aluminosilicate-based phosphors started in 1988. Anorthite (CaAl2Si2O8), having a triclinic crystal system with space group I1 [276], was the first aluminosilicate phosphor, reported by Angel et al. in 1988. Later, some new calcium aluminosilicate materials were reported, based on the combination of CaO–Al2O3–SiO2 ternary system, and many of these were selected as the host resources for efficient phosphors, such as CaAl2Si2O8:Eu2+ [277], CaAl2Si2O8:Eu2+, Mn2+[278], CaAl2Si2O8:Eu2+, Ce3+ [279], and Ca2Al2SiO7:Ce3+, Tb3+ [280]. There are different types of aluminosilicates based on their structure, such as andalusite, kyanite, and sillimanite, having the chemical formula Al2SiO5 (Al2O3.SiO2). The name kyanite is derived from the Greek word kuanos, at times referred to as kyanos, meaning deep blue, and sillimanite is named after the American chemist Benjamin Silliman (1779–1864) [281]. These have different crystal structures. Another group of aluminosilicates is feldspar, in which the Si4+ ions in silicates are replaced by Al3+ ions; hence, the charge must be balanced by other positive ions such as Na+, K+, and Ca2+ ions. Some examples of the feldspar group are Sanidine [(K, Na)AlSi3O8]4Orthoclase [(K, Na)AlSi3O8]4Albite [NaAlSi3O8]4Anorthite Ca[Al2Si2O8]
Two mixed-ligand transition metal coordination polymers: crystal structures and prevention effect on chronic obstructive pulmonary disease
Published in Inorganic and Nano-Metal Chemistry, 2022
Xiao-Jun Chen, Hong-Juan Wang, Wei Shan
Single-crystal structure analysis reveals that 1 crystallizes in the triclinic crystal system of the P-1 space group. The asymmetric unit of 1 consists of one crystallographically independent Zn(ii) ion, one OBPB ligand and two halves of a tfbdc2− ion. As shown in Figure 1a, each Zn1 is four-coordinated with a distorted tetrahedral coordination geometry to two O atoms from two tfbdc2− ligands and two N atoms from two OBPB ligands. The Zn–O distances are 1.9509(14) and 1.9568(15) Å, and the Zn–N distances are 1.9889(17) and 2.0030(17) Å. The carboxylate groups of the tfbdc2- ligands adopting monodentate coordination modes μ1–η1:η0 link Zn(ii) to develop a 1 D zig-zag chain (Figure 1b). The neighboring 1 D chains further form a 2 D layered network via OBPB ligands along the bc plane with the rhombic window size of 19.745×12.263 Å2 (Figure 1c). Interestingly, two OBPB ligands link two Zn(ii) cations to form an approximately rhombic {Zn2(OBPB)2} metallamacrocycle. The supplementary interior angles are 72.023(18)° and 107.977(21)°. Topologically, all the organic ligands can be considered linkers, and each Zn(ii) is regarded as a 3-connected node. The whole network of 1 shows hcb topology with a point symbol of (63) (Figure 1d).